Monolayer Doping Precursors for Uniform Shallow Junctions
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Solution Overview
Problem
Current monolayer doping techniques face challenges in achieving uniform dopant incorporation and stability, particularly in three-dimensional semiconductor structures, due to issues like substrate damage from ion implantation and non-uniform dopant distribution, and the use of toxic compounds requires redesign of equipment and careful handling.
Innovation Solution
A doping process involving the application of a dopant film that bonds to the substrate via hydrogen or covalent bonding, followed by encapsulation and rapid thermal processing, using dopant compositions such as aqueous or glycol solutions, arsenic, phosphorus, or boron compounds with specific ligands, or organodopant precursors, to enhance dopant migration and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ion implantation is used for doping, then doping efficiency is improved, but substrate damage occurs rendering the substrate unusable or in need of reworking
Solution Approach 1:
The patent replaces the mechanical ion implantation process with a chemical monolayer doping process. Instead of physically bombarding the substrate with ions, the invention uses chemical solutions to deposit dopant precursors that form monolayers on the substrate surface, followed by thermal processing to drive dopant incorporation. This substitution eliminates mechanical damage while achieving effective doping.
Solution Approach 2:
The patent changes the fundamental parameters of the doping process by transitioning from high-energy physical ion implantation to low-energy chemical deposition followed by controlled thermal processing. The dopant is introduced as molecular precursors in solution form rather than as energetic ions, fundamentally altering the energy state and interaction mechanism with the substrate.
2Productivity
If ion implantation or plasma immersion is used, then doping is achieved, but uniform dopant incorporation in three-dimensional structures is difficult
Solution Approach 1:
The patent applies local quality by allowing the chemical solution to penetrate and deposit dopant precursors uniformly across complex three-dimensional surfaces. The liquid phase enables the solution to access recesses and sidewalls of 3D structures, ensuring uniform monolayer formation throughout the entire surface topology, including areas that would be difficult to reach with directional ion implantation.
Solution Approach 2:
The patent utilizes the fluid properties of liquid solutions to achieve uniform dopant deposition. The hydraulic action of the solution allows it to flow over and into three-dimensional structures, ensuring consistent coverage and monolayer formation across complex geometries, unlike gas-phase or solid-state methods.
3Ease of manufacture
If monolayer doping with dilute solutions is used, then simple wet processing is achieved, but large amounts of solvent waste are generated
Solution Approach 1:
The patent addresses solvent waste through rinsing steps that remove excess solution and through process design that minimizes solvent consumption. The rinsing process recovers and removes unreacted dopant precursors and solvent, reducing waste while maintaining the simplicity of the wet processing approach.
4Productivity
If toxic dopant compounds such as arsenic are used in monolayer doping, then desired dopant functionality is achieved, but equipment redesign is required to mitigate human exposure
Solution Approach 1:
The patent uses organic precursor molecules as intermediaries to deliver toxic dopant elements like arsenic to the substrate. Instead of using pure toxic compounds, the invention employs organometallic or organic-inorganic hybrid precursors that contain the dopant element in a less hazardous form. These precursors decompose during thermal processing to release the active dopant, thereby reducing human exposure risks while maintaining dopant functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process achieves improved dopant uniformity and stability, reducing random fluctuations and solvent waste, while allowing for the use of less toxic compounds and avoiding high decomposition temperatures, thus enabling effective ultra-shallow junction formation in semiconductor products.
Implementation Method 1
applying to a substrate a film of dopant material that bonds to the substrate by at least one of hydrogen bonding and covalent bonding
Implementation Method 2
applying to a substrate a film of dopant material that bonds to the substrate by at least one of hydrogen bonding and covalent bonding
Implementation Method 3
subjecting the encapsulated film to rapid thermal processing to cause dopant from the dopant material to migrate into the substrate
Implementation Method 4
subjecting the encapsulated film to rapid thermal processing to cause dopant from the dopant material to migrate into the substrate
Implementation Method 5
encapsulating the film on the substrate with an encapsulant material
Data Source
AI summary
A doping process is described, which includes applying to a substrate a film of dopant material that bonds to the substrate by at least one of hydrogen bonding and covalent bonding; encapsulating the film on the substrate with an encapsulant material, and subjecting the encapsulated film to rapid thermal processing to cause dopant from the dopant material to migrate into the substrate. The film of dopant material is applied from a dopant composition selected from among: (i) dopant compositions comprising an aqueous or glycol solution comprising an inorganic dopant compound; (ii) dopant compositions comprising an arsenic, phosphorus, boron, or antimony compound in which ligands or moieties coordinated to an arsenic, phosphorus, boron, or antimony central atom have coordination bond energies that are lower than those associated with coordinating bonds of said central atom to oxygen or carbon; (iii) dopant compositions comprising a coordinated moiety that selectively and covalently bonds to the substrate; (iv) dopant compositions comprising a compound that undergoes hydrolysis and alcoholysis to covalently bond a dopant functionality to the substrate in said film of dopant material; (v) dopant compositions comprising precursor vapor of an organodopant compound; (vi) dopant compositions interactive with a surface functionality of the substrate to bind the dopant composition to the substrate, wherein the substrate comprises a silicon surface comprising said surface functionality; (vii) dopant compositions interactive with the substrate to covalently bond with a pretreated and/or modified silicon surface thereof; and (viii) dopant compositions interactive with the substrate to bond with the substrate on a silicon surface thereof that has been modified by a treatment comprising at least one of: (A) contacting the silicon surface with a chemical solution; (B) exposing the silicon surface to plasma; and (C) exposing the silicon surface to ultraviolet radiation.